ChocolateHigh Blood Pressure

The benefit of small amounts of dark chocolate on blood pressure

In a small group of people with above-optimal blood pressure, including “small amounts of polyphenol-rich dark chocolate as part of a usual diet efficiently reduced blood pressure,” according to researchers from the University Hospital of Cologne in Germany.

Unfortunately, the researchers could only postulate the long term benefit of blood pressure control, rather than actually show it in this group of volunteers.

First, the details.

  • 44 adults had untreated upper-range prehypertension (under 140/90 mmHg) or stage 1 high blood pressure (BP; less than 159/99 mmHg)
  • They were randomly assigned to take 6.3 grams (30 kcal, about a teaspoon) per day of dark chocolate containing 30 mg of polyphenols or matching polyphenol-free white chocolate.

And, the results.

  • After 28 weeks, eating dark chocolate was associated with a significant 3 mmHg reduction in systolic BP and a 2 mmHg reduction in diastolic BP.
  • There were no changes in body weight, blood levels of lipids, or blood sugar.
  • The prevalence of high blood pressure declined from 86% to 68%.
  • The BP decrease in the dark chocolate group was accompanied by the appearance of cocoa phenols in the blood.

OK. Here’s some background for perspective.

A review of the medical literature conducted last year by researchers at Harvard University concluded that “chocolate may exert beneficial effects on cardiovascular risk via effects on lowering blood pressure, anti-inflammation, anti-platelet function, higher HDL [good cholesterol], decreased LDL [bad cholesterol].”

The reason for this is probably the flavonoid content of chocolate, which might act to reduce the risk of death due to heart diease. The problem in settling this issue is that the results from epidemiologic studies in large populations have been inconclusive — probably because of limitations in their design.

What’s needed, according to the Harvard researchers, and the researchers from Cologne, are “larger randomized trials to definitively investigate the impact of chocolate consumption on long-term cardiovascular outcomes.”

This study was in a small population. And although it showed improved blood pressure, the short follow-up made it impossible to report beneficial changes in morbidity or mortality in the dark chocolate group — which is really what we need to know.

An easy to read review of the health effects of chocolate can be found here.

7/4/07 10:05 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.